The reason a brain dump stalls is almost always that you started sorting while you were still dumping.
Both are useful. Doing them at once is not: the moment you have to decide where something goes, the next three things you were about to remember quietly disappear.
Dump first, then sort
The top two-thirds of the sheet is one large empty area with no lines and no structure, because structure is an invitation to categorise. Write everything, in any order, in any handwriting. Nothing is too small and nothing is too obvious.
Only when you have run dry do you look at the bottom third.
Three columns and nothing else
Now. Today, genuinely. Next. The real answer for most things. Later. Which is not a bin — it is permission to stop thinking about it.
Three is the most decisions anybody can make quickly about thirty items. Adding a fourth priority tier is how a sorting system becomes another thing to avoid.
The “not mine” box
The small box in the corner is for the things on your mind that are somebody else’s to do. They take up exactly as much room in your head as your own tasks and you cannot action any of them. Naming them is the only move available, and it works better than it sounds.
Print a few
Free, one page, print a small stack and leave them where you sit down. Doing this on paper rather than in an app is not nostalgia — it removes every step between noticing you are overwhelmed and starting.